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Leakage Rates ‘Threaten Green Benefits of Natural Gas’

Failure to reduce methane leaks has the potential to eliminate much, if not all, of the greenhouse gas advantage of natural gas over coal, according to research published in the Proceedings of the National Academy of Sciences.

Methane is the main ingredient in natural gas and burns cleaner than other fossil fuels when combusted, but un-combusted methane is a greenhouse gas many times more potent than carbon dioxide – the principal contributor to man-made climate change. As a result the gas’s leakage from production and transportation has the potential to remove any environmental benefits it boasts over traditional fuels, according to Greater Focus Needed on Methane Leakage from Natural Gas Infrastructure, whose five authors hail from Princeton, Duke, the Rochester Institute of Technology and the Environmental Defense Fund.

Assuming the EPA’s 2009 leakage rate of 2.4 percent (from well to city) is correct, new natural-gas combined cycle power plants reduce climate impacts compared to new coal plants, and do so as long as leakage remains under 3.2 percent.

However, assuming the EPA’s estimates for leak rates, compressed natural gas-fueled vehicles are not a viable mitigation strategy for climate change because of methane leakage from natural gas production, delivery infrastructure and from the vehicles themselves, the paper finds. For light-duty CNG cars to become a viable short-term climate strategy, methane leakage would need to be kept below 1.6 percent of total natural gas produced. This is approximately half the current amount for well to wheels leakage.

Methane emissions would need to be cut by more than two-thirds to immediately produce climate benefits in heavy-duty natural gas-powered trucks. At current leakage rate estimates, converting a fleet of heavy duty diesel vehicles to natural gas would result in nearly 300 years of climate damage before any benefits were achieved, the report says.

A methane leakage model created by the Environmental Defense Fund and based on the science described in the PNAS paper allows anyone to test a range of scenarios to quantify the climate benefits, or damages, of natural gas production and usage given specific methane leakage rates.

Companies the world over have been quick to buy CNG fleets and highlight their green credentials as a result. In January, AT&T ordered 1,200 Chevrolet Express compressed natural gas cargo vans while Waste Management announced a pilot program to introduce natural gas powered Rotopress waste collection trailers. In June last year, Chicago and Los Angeles rolled out CNG-fueled fleets of Ford Transit Connect Taxis.

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4 thoughts on “Leakage Rates ‘Threaten Green Benefits of Natural Gas’

  1. Obviously being a greenhouse gas (like H20 ans Co2 does not dictate the temperature. The equilibrium temperature is dictated by the amount of energy that comes in, since all the GHG does is reradiate it back out to space to maintain the equilibrium. The variation in temperature is dictated by the amount of energy coming in. both every morning and every 12 years (jupiter orbit)& 60 years we get an energy peak forced by the orbit of JUpiter/Saturn. The amount of GHG just maintains the equilibrium. IF less is coming in then the excess CO2 or water vapor is just not used. These climate scientists just do not understand equilibrium energy flows. Why do you think that the temperature does NOT rise when it rains when there is excess GHG H20 in teh air?

  2. Obviously being a greenhouse gas (like H20 ans Co2 does not dictate the temperature. The equilibrium temperature is dictated by the amount of energy that comes in, since all the GHG does is reradiate it back out to space to maintain the equilibrium. The variation in temperature is dictated by the amount of energy coming in. both every morning and every 12 years (jupiter orbit)& 60 years we get an energy peak forced by the orbit of Jupiter/Saturn. The amount of GHG just maintains the equilibrium. IF less is coming in then the excess CO2 or water vapor is just not used. These climate scientists just do not understand equilibrium energy flows. Why do you think that the temperature does NOT rise when it rains when there is excess GHG H20 in the air? The amount of GHG/CO2/H20 does NOT dictate the temperature, contrary to the environmentalists beliefs.

  3. Thanks John for the information. I would like to believe that the information that science and media rely on are not near complete to be able to determine the GHG effect and the effect on the global warming scare as well. I can tell you have some crucial knowledge to address this topic. Thank you for you input and response. By the way, where would I find more information to support the idea? And what is your experience/training? Thank you, Robert Fraley
    (Student advocate for Natural Gas Vehicles)

  4. The comment by John is full of misinformation, and demonstrats a near-complete lack of scientific understanding.

    “The equilibrium temperature is dictated by the amount of energy that comes in, since all the GHG does is reradiate it back out to space to maintain the equilibrium” – this statement is false. Equilibrium is maintained when the outgoing energy exactly balances the incoming energy, but the temperature that is required for this balance to occur is influenced by the amount of GHG present in the atmosphere. And GHGs do not simply “reradiate [energy] back out to space” – instead, they act to redistribute (or to transform) radiative energy as heat energy within the atmosphere.

    “The variation in temperature is dictated by the amount of energy coming in” – only partly true. It is also dictated by the amount of GHGs in the atmosphere, as well as other influences like cloud cover, the amount of aerosols in the atmosphere, changes in surface albedo from many different causes, etc., etc.

    The comments about 12 and 60 year forcings related to the orbits of Jupiter and Saturn are completely off base. There are no such significant forcings – period.

    “IF less is coming in then the excess CO2 or water vapor is just not used” – this statement likewise has no basis in reality.

    “These climate scientists just do not understand equilibrium energy flows” – hah. So you are claiming that climate scientists with years of education and experience, somehow do not understand basic physics? And that you do understand it, despite your other claims that clearly demonstrate otherwise?

    “Why do you think that the temperature does NOT rise when it rains when there is excess GHG H20 in the air?” – the answer to this is straightforward. The rain first condensed at altitude. The process of condensation released heat into the surrounding environment (at altitude). When it rains the sun is typically blocked, and when it is then there is less incoming radiation and lower local ground temperatures. Some of the rain that falls might quickly re-evaporate, which absorbs heat from the surrounding environment (ground level) – which might further lower local ground temperatures. And the rain, falling from high altitudes, is often colder than local ground temperatures, which leads to even further local cooling. Any other questions?

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